The present invention comprises a power tool attachment for beveling pipe. It is directed to the need for such tools that are portable for field use in beveling the ends of relatively large diameter plastic pipe.
It is often desirable when assembling long sections of plastic pipe in the field, to form a beveled end on one or both ends of the pipe sections in order to more securely fit them together and to facilitate gluing operations. Although some pipe is manufactured with beveled ends, it is usually necessary to form a bevel on the end of a pipe that has been cut to length at a particular job site. When it becomes necessary to bevel the end of a pipe at a job location today, manual procedures are used. The bevel is hand-formed by utilizing a file or rasp. This is a very tedious and time consuming task. Further, when the pipe ends are beveled by hand, there is no guarantee that the resulting bevel will fit properly within the adjoining pipe section. It therefore becomes desirable to obtain a tool by which consistent and precise angular bevels may be produced quickly and efficiently at the ends of pipes.
U.S. Pat. No. 3,636,803 to Miller granted on Jan. 25, 1972 discloses a hand-operating pipe beveling tool. This tool includes a knife for scraping or cutting a bevel on the outside surface of a pipe and an end trimming blade that functions to square the end of the pipe. The knife and blade are held on a crosspiece that is rotatably mounted to a central mandrel. This mandrel is necessarily the same diameter as the inside diameter of the pipe to be beveled. Thus, different mandrels must be utilized for different size pipe. Further, the beveling process is performed by hand without the advantage of using power equipment.
U.S. Pat. No. 3,699,828 to Piatek, which was granted on Oct. 24, 1972 discloses a pipe grooving tool. Here, a form of "routing" tool is utilized in combination with a series of clamp rollers in order to locate a cutting tool relative to the outside surface of a pipe. The rollers enable the tool to be moved about the pipe circumference to thereby allow the cutting tool to form an annular groove about the outside surface of the pipe. Four guiding rollers are described and are situated in pairs on directly opposite sides or surfaces of the pipe.
U.S. Pat. No. 3,162,002, granted to J. D. Hogden et al on Jan. 5, 1965, discloses a pipe cutter. Again, this device utilizes a central mandrel that fits within the core of a pipe to center and support the working elements of the cutting assembly for rotation about the mandrel axis. The mandrel size restricts the size of pipe. Different mandrels would be required where substantially different diameter pipes are to be cut. U.S. Pat. No. 3,103,140, granted to E. B. Connelly on Sept. 10, 1963, discloses a combination tool head for finishing pipe ends. This tool is probably exemplary of the form of tools utilized in pipe manufacturing operations to produce outside bevels at the ends of newly manufactured pipes. This device is substantially stationary in nature and is thus incapable of being utilized in field practice.
U.S. Pat. No. 3,540,328 to R. G. Foss, granted on Nov. 17, 1970, discloses an apparatus for tapering the ends of laminated plastic pipe. Again, this device makes use of a central support mandrel which is placed within the pipe core and expanded to tightly grip the pipe from within and provide rotational support for the pipe beveling structure mounted thereto. A cutting tool in the form of a number of knives is provided to form the desired bevel in the pipe as the tool is rotated about the axis of the stationary mandrel.
U.S. Pat. No. 3,202,190 to J. B. Gill, granted on Aug. 24, 1965, discloses an adjustable pipe machining tool. This device is disclosed as either being manually operable or motor powered to produce a beveled or reduced shoulder at the end of a pipe. Although no central support mandrel is disclosed in the drawings, the specification makes note that "the arbor may be of any suitable type which may be securely mounted in the end of the pipe to be machined and with the arbor shaft concentric with the pipe". The specification makes particular reference to a form of arbor illustrated in U.S. Pat. No. 2,607,376. The Gill apparatus is similar to the above cited apparatus in that it is dependent upon a central arbor or mandrel to locate the rotational axis of the cutting head.
The present invention does not make use of a central arbor or mandrel that fixes the tool itself for rotation about the axis of the arbor or mandrel. It has been found more productive to provide some means for moving a cutting tool about the exact pipe periphery as defined by the configuration of the pipe at its end. The result is a uniform bevel about the pipe. With the mandrel forms of beveling devices, a non-uniform bevel may be obtained where the pipe end has been slightly disfigured or is oval in configuration rather than being circular. This is a problem peculiar to plastic pipe. By utilizing a portion of the end surfaces of the pipe to guide the rotary cutter, I am able to form consistent and uniform bevels. Furthermore, by providing adjustment provisions, the present attachment is adaptable to fit a wide range of pipe diameters. A still further distinguishing characteristic of my invention is that it is adapted to be used in conjunction with standard forms of portable electric power tools. Other forms of beveling tools as disclosed above are either necessarily hand operated or contain their own integral power unit. The hand operated devices are adequate to a limited degree for field use but are relatively slow in comparison to the powered devices. On the other hand, the powered forms of beveling tools are necessarily expensive and their cost is seldom justifiable or is recovered only over an extended period of time.